Regulation Of Myometrial Gene Expression By Oestrogen And Progesterone: The Use Of A Cell Culture Model To Mimic The In Vivo Conditions Of Pregnant Human Uterus

Abstract

Pregnancy and labour are physiological events controlled by a complex interplay between maternal and foetal factors. These processes are diverse and specific to each species, hence simple extrapolation from model organisms to humans is challenging. Nonetheless, understanding the underlying regulatory mechanisms involved is of utmost importance in the diagnosis and treatment of preterm and post-term labour. Throughout pregnancy the uterus maintains a quiescent state and develops a strong and rhythmic contraction towards parturition. Progesterone and oestrogen play vital roles in this transformation. In most mammals, high concentrations of progesterone dominate pregnancy (pro-relaxatory), while oestrogen (pro-contraction) levels take over towards labour. However, in humans the circulating levels of both progesterone and oestrogens remain high throughout pregnancy. Hence, functional withdrawal of progesterone and responsiveness to oestrogen is believed to occur more at the molecular level than at the circulating level. This study, therefore, focused on developing a myometrial smooth muscle cell culture model to evaluate the transcriptomic effect of steroid hormone treatment on cultured human uterine smooth muscle cells (hUtSMCs). Microarray-based gene expression analysis was performed on RNA isolated from hUtSMCs, treated with 17beta-estradiol (E2) and progesterone (P4) (separately or in combination) in addition to functional withdrawal of P4 with mifepristone (RU486) in order to identify differentially expressed genes associated with each treatment. Functional P4 withdrawal by RU486 altered the expression of these genes favouring myometrial contraction, whereas (P4+E2)-treatment favoured myometrial quiescence. The findings of these studies are in line with published reports on labouring and nonlabouring myometrium across various species, confirming that the cultured cell model system developed in the present study responds to hormonal treatments in a similar manner to that of the myometrium in vivo. The myometrial cell culture system is therefore an additional research tool that can be used for functional studies of human pregnancy and labour.